Zubrin citisism

From: spacesettlers@yahoogroups.com
[mailto:spacesettlers@yahoogroups.com] On Behalf Of Dan Wylie-Sears

> > Mars is a waste. Too much gravity to make any mining affordable.
>
> That depends on the value of the materials, and the technology
> available to mine and launch them. By the time we deplete the
> main belt, the Kuiper Belt, and various moons (assuming we don't
> kill ourselves off first), mining Mars will definitely be feasible.

Yes, but by the time we've depleted all the various resources you've
mentioned, I think we'll be several millenniums into the future. In
which case technology will be so different that most any prediction we
make today will be wrong.

My viewpoint is that advances of technology will never change the fact
that obtaining resources from shallow gravity wells will require less
energy than from steep ones. That will always make a difference,
economically speaking. Marvelous technological advances may reduce the
magnitude of that difference, but will never eliminate it.

> Possibly even before, depending on the technology. If mass
> drivers, catchers, and energy sources all fulfill all our fondest
> hopes, then it might be simpler, for many materials anyway, to
> throw stuff from Mars than to go chasing down asteroids.

The problem with mass drivers for Mars is that while Mars doesn't have
much of an atmosphere, it's still enough to make horizontal EM launch
off the surface more difficult and problematic than launch through a
vacuum. Such launch from the Martian surface might be easier than from
the Earth's surface, but that's not saying much; it's fairly impractical
from the Earth's surface.

Regards,

Mike Combs